摘要：
Reservoir porosity obtained from time-domain induced polarization (TDIP) well logging plays a vital role in estimating the hydraulic properties and obtain the reservoir parameters in a water-flood oil-field. Improving the inversion accuracy of the reservoir porosity can enhance the oil recovery in the water-flood oil-filed. Evaluating reservoir pore size distribution through induced polarization decay curve is confronted with the problems of poor applicability of data pre-processing, low accuracy and lacking of evaluation criteria for inversion results of pore size distribution. The basic principles of TDIP are introduced and the relationship between pore relaxation time and pore diameter is given. Combining the mathematical characteristics of polarization decay curve data, the performance and the limitations of existing pre-processing algorithms are analyzed and pointed out, respectively. An improved data pre-processing algorithm using the spatial characteristics of linear transformation based on migration Hankel matrix is proposed, and this method improves the inversion accuracy of pore size distribution greatly. In the engineering application, 2-logarithmic sampling method is proposed to sample the polarization decay data for more efficient petroleum exploration with less sample points. The different regularization methods, regularization matrix and regularization parameter determination methods are compared and analyzed for the inversion of the pore size distribution. The numerical simulation experimental results show that the stability and accuracy of Truncated Singular Value Decomposition - Generalized Cross Validation (TSVD-GCV), Truncated Singular Value Decomposition - L Curve (TSVD-L) and Tikhonov-I-L are appropriate for the inversion of pore size distribution. Because of the truth that the pore size distribution of rock is unknown, Backus-Gilbert (BG) theory is introduced to evaluate the inversion results of rock polarization decay curve data of a mining area in Jilin Province. The rock sample experiment shows that the TSVD-GCV inversion algorithm has the best performance.
关键词：
Microbolometer array;Responsivity;Substrate temperature compensation
摘要：
For a normal microbolometric focal plane array, the microbolometric infrared responsivity varies with its substrate temperature fluctuations because of the semiconductor characteristics of the microbolometer array. The relationship between the microbolometric infrared responsivity and substrate temperature is theoretically discussed in this paper. Above the discussion, a new substrate temperature compensation method is proposed for microbolometric focal plane array without TEC. The microbolometric focal plane array is based on a kind of high-speed CMOS readout integrated circuit, of which the microbolometric infrared response voltage signal can be directly read out without infrared response current integration. The bias current for the microbolometer with the proposed substrate temperature compensation method can be adjusted according to the substrate temperature change to achieve a steady microbolometric infrared responsivity. This kind of substrate temperature compensation method is theoretically strict and has been experimentally verified in our laboratory, which is potential for future high-speed, lower-power and small-pixel microbolometric focal plane array.
摘要：
In this paper, we develop a theoretical principle to calculate the direct and converse magnetoelectric (ME) coupling response of ferromagnetic/ferroelectric composites with 2-2 connectivity. We first present an experimentally based constitutive equation for Terfenol-D, and then build the mechanism of domain switch for the ferroelectric phase. In the latter, the change of Gibbs free energy, thermodynamic driving force and kinetic equations for domain growth are also established. These two sets of constitutive equations are shown to capture the experimental data of Terfenol-D and PZT, respectively, well. For the direct effect under an applied magnetic field, the induced electric field and the overall ME coupling coefficient are determined. For the converse effect under an applied electric field, the induced magnetization and the excited magnetic field are obtained. Both the induced electric filed under direct effect and the excited magnetic field under converse effect are shown to display the hysteretic characteristics, and also in good agreement with experiments. We conclude that the developed theory can both qualitatively and quantitatively reflect the essential features of nonlinear direct and converse ME coupling of the multiferroic composites.
摘要：
Most previous studies assumed noise to be unbounded Gaussian. Here the effects of nonGaussian cross-correlated sine-Wiener (CCSW) bounded noises on temporal regularity and spatial synchronization of coupled neurons are investigated in regular and small-world networks of the FitzHugh-Nagumo (FHN) neurons. For regular neuronal networks, as crosscorrelation time of CCSW noises is increased, CCSW noises-induced temporal coherent resonance occurs at appropriately cross-correlation time of CCSW noises, and spatial synchronization in neuronal network is always impaired. In addition, the increasing degree of correlation of CCSW noises may enhance or impair temporal regularity, which is dependent on cross-correlation time. On the other hand, the increasing degree of correlation of CCSW noises destroys spatial synchronization or has no effect on spatial synchronization. For small world neuronal network, CCSW noises-induced enhancement of temporal regularity and degradation of spatial synchronization are still observed. Furthermore, the increasing rewiring probability make spatiotemporal pattern more order in time and in space. If delay is introduced into small world network, the aforementioned CCSW noises-induced phenomena still exist. Meanwhile, delay let spatiotemporal pattern more disorder. (C) 2019 Elsevier B.V. All rights reserved.
关键词：
dynamic instability;graphene system;nonlinear phase shift;optical ring cavity
摘要：
Controlling dynamic behaviors, such as instability and chaos, in various systems has been a central matter of nonlinear physics in recent years. Here we employ an effective density-matrix method for the study of laser beam propagation through an optical ring cavity containing Landau-quantized graphene nanostructures. By taking into account the linear and nonlinear phase shifts, we detailedly investigate and characterize the nonlinear dynamic behaviors of the transmission field and the results show that the system exhibits dynamic instability. The start and termination, as well as the periodicity of this dynamic oscillations inside the optical cavity can be manipulated by the experimentally achievable parameters, such as the laser intensity and frequency detuning. Such dynamic responses are attributed to the competition between optical saturation of the incident field and population oscillations induced by the control field in graphene system.
作者：
Zhang, Duo*;Yu, Rong;Sun, Zhaoyu;Ding, Chunling;Zubairy, M. Suhail
期刊：
Journal of Physics B: Atomic, Molecular and Optical Physics,2019年52(3):035502 ISSN：0953-4075
通讯作者：
Zhang, Duo
作者机构：
[Zhang, Duo; Sun, Zhaoyu] Wuhan Polytech Univ, Sch Elect & Elect Engn, Wuhan 430023, Hubei, Peoples R China.;[Zubairy, M. Suhail; Zhang, Duo] Texas A&M Univ, IQSE, College Stn, TX 77843 USA.;[Zubairy, M. Suhail; Zhang, Duo] Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA.;[Yu, Rong; Ding, Chunling] Sch Sci, Wuhan Inst Technol, Wuhan 430205, Hubei, Peoples R China.;[Zubairy, M. Suhail] Huazhong Univ Sci & Technol, Sch Phys, Wuhan 430074, Hubei, Peoples R China.
通讯机构：
[Zhang, Duo] W;[Zhang, Duo] T;Wuhan Polytech Univ, Sch Elect & Elect Engn, Wuhan 430023, Hubei, Peoples R China.;Texas A&M Univ, IQSE, College Stn, TX 77843 USA.;Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 USA.
关键词：
3D atom localization;standing wave;probe absorption
摘要：
A new scheme for three-dimensional (3D) atom localization is proposed based on measuring the probe absorption spectra in a four-level diamond-configuration atomic system, in which the atom interacts with three orthogonal standing-wave laser fields. Due to spatial-dependent interaction between atom and fields, position information of the atom can be obtained by measuring the absorption spectra of the weak probe field. The results show that atom localization properties can be significantly improved and some interesting spatial localization structures such as double-layer lantern-like, single-layer lantern-like, gourd-like, cylinder-like, and ellipsoid-like patterns can be achieved when we adjust system parameters properly. Most importantly, we can find the atom at a particular position in 3D space with 100% probability under appropriate conditions.
关键词：
global quantum discord;quantum discord;quantum phase transitions;two-dimensional lattices
摘要：
Global quantum discord (GQD) in two‐dimensional (2D) transverse‐field Ising models on N × N square lattices at zero temperature and finite temperatures are studied. First, the GQD G(ρ2×2) defined on the reduced density matrix ρ2×2 of a 2 × 2 sub‐square in the center of the N × N lattices, with N=4, 5, 6, 7, ∞ is studied. It is found that G(ρ2×2) shows little size dependence in the strong‐field and weak‐field limit, and presents dramatic size dependence in the middle‐field region. The results are explained by short‐range correlations in non‐critical regions and long‐range correlations in critical regions of the models, respectively. Then the scaling behavior of the GQD G(|ψg〉) of the ground states for the entire N × N squares is studied. It is found that G(|ψg〉) contains a 1D contribution (corresponding to the side length of the squares) and a 2D contribution (corresponding to the area of the squares). Furthermore, the effect of thermodynamic fluctuations on GQD by investigating the thermal‐state GQD G(e−HkBT) is considered. In high‐temperature regions, GQD is always destroyed by thermodynamic fluctuations for any strength of the magnetic field. However, in low‐temperature regions, some thermal enhancement of GQD under weak fields and some thermal robustness of GQD under strong fields is observed. The results are explained by the low‐lying energy states and the energy gap of the models. Various progresses have been made in understanding quantum correlations in 1D quantum lattices. However, our understanding for 2D quantum lattices is still at a low level. How would quantum correlations scale with the size of the 2D lattices? How would external physical parameters affect the strength and the robustness of quantum correlation in the 2D lattices? Here, these questions will be answered in the 2D transverse‐field Ising squares.
关键词：
quantum coherence and coherence measures;coherent control;cooling and trapping;spontaneous emission
摘要：
The actual location of an atom in three-dimensional (3D) space is described by spatial-dependent atom-field interaction, which has potential applications in many fields, including optical imaging techniques, 3D nanolithograghy, Bose–Einstein condensation, and dual-measurement of center-of-mass wave function. Here, we propose a scheme to realize single atom localization in 3D space based on double-channel interactions. By exploiting the property of the spontaneously emitted photon, high-precision 3D atom localization, such as sphere-like pattern, ellipsoid-like pattern, funnel-like pattern, and ring-like structure can be achieved. These localization phenomena are the consequence of the quantum interference among multiple decay pathways. Furthermore, we show that with the system parameters specifically tuned, a high degree of localization of atom is enabled in a sub-wavelength range. Different from other 3D schemes, our proposed system is more robust under the influence of double-channel interactions. Our findings could be instructive for understanding the localization mechanisms in such a system with competitive decay channels.
摘要：
Feature extraction is a key problem in spectral analysis. Spectrum collected with spectrometer have latent low-rank component. If spectrum can be represented as a superposition of low-rank component and an approximation term, the spectrum feature is obtained. In this paper, a novel low-rank based infrared spectral feature extraction method is proposed. Employing a slide window to convert a single spectrum into a matrix, which can be decomposed as the superposition of a low-rank component and feature. In machine learning, nuclear norm is employed to approximate to low-rank minimization. Thus, the model can be written as a combination of the nuclear norm and an approximation term. We have proposed an efficient algorithm with singular value decomposition to the model. Solving the model, we obtain the latent low-rank component in spectrum. The feature is obtained via derivative of original and low-rank approximation. Then the quantitative analysis model is directly built with the feature. The advantage of proposed method is that extraction procedure of one spectrum is not affected by other spectrum. Extensive experiments are conducted with four public data sets and experimental results demonstrate that our proposed feature extraction method can lead to accuracy improvements over state-of-the-art methods. (C) 2017 Elsevier GmbH. All rights reserved.
关键词：
Maximum correntropy;Partial least squares;Regression;Robustness
摘要：
Partial least squares (PLS) has been extensively used to solve problems such as infrared quantitative analysis, economic data analysis, object tracking. PLS finds a linear regression model by projecting the predicted variables and the response to a new space. A major drawback of existing PLS methods is that regression coefficient will be affected by outliers. Thus, partial least squares experience significant performance degradation when gross outliers are presented. The problem of robust partial least squares has been relatively unexplored in Chemometrics and other related fields. In this paper, a new maximum correntropy based partial least squares is proposed to build robust model. We then proposed a solution algorithm for proposed model. Moreover, we also conducted convergence analysis to mathematically support the proposed model. Extensive experiments are conducted with four public data sets and experimental results demonstrate that our proposed regression method can lead to better accuracy to existing methods. (C) 2017 Published by Elsevier GmbH.
摘要：
Based on the discussion of infrared signal readout structure for microbolometric focal plane array, the microbolometric infrared response signal bandwidth is theoretically analyzed in this paper. The infrared response signal channel in microbolometric focal plane array normally consists of several major parts and every one of these different parts has its own signal bandwidth. The signal bandwidth expressions for these parts are theoretically deduced on their physical thermal model or integrated circuit structures, and some key parameters to decide the microbolometric signal bandwidth are revealed in these expressions. These signal bandwidth expressions are theoretically strict and can be utilized to optimize the final infrared response signal bandwidth for any practical microbolometric focal plane array. These theoretical expressions have been successfully applied to guiding the microbolometer structure and readout integrated circuit design in our laboratory, and are useful for a microbolometric focal plane array to have an optimized signal bandwidth and achieve excellent signal-to-noise performance as well.
摘要：
In this paper, we carry out a theoretical investigation on the population dynamics of graphene system under continuous-wave (cw) laser and chirped pulse excitation. Results of our numerical simulations reveal that complete population transfer from an initially occupied ground state to the initially unoccupied excited states can be achieved by choosing appropriate values of the chirp rate, the laser field intensity and frequency, as well as other system parameters. Also, we observe coherent Rabi-like population oscillations between the initial ground state and the excited final state. It is induced by the combined effect of cw and chirped-pulse laser fields. These results will contribute to the understanding of carrier-carrier and carrier-phonon interactions in graphene system, and may find applications in graphene-based high-speed electronic and optoelectronic devices.
摘要：
In a previous study, we have proposed a procedure to study global quantum discord in 1D chains whose ground states are described by matrix product states [Z.-Y. Sun et al., Ann. Phys. 359, 115 (2015)]. In this paper, we show that with a very simple generalization, the procedure can be used to investigate quantum mixed states described by matrix product density operators, such as quantum chains at finite temperatures and 1D subchains in high-dimensional lattices. As an example, we study the global discord in the ground state of a 2D transverse-field Ising lattice, and pay our attention to the scaling behavior of global discord in 1D sub-chains of the lattice. We find that, for any strength of the magnetic field, global discord always shows a linear scaling behavior as the increase of the length of the sub-chains. In addition, global discord and the so-called “discord density” can be used to indicate the quantum phase transition in the model. Furthermore, based upon our numerical results, we make some reliable predictions about the scaling of global discord defined on the n × n sub-squares in the lattice.
摘要：
Dual frequency comb generation has been the focus of many recent research efforts owing to its viability in a myriad of applications, ranging from precision measurement to high-speed optical communications. Here, with the state of the art of a single quantum dot (QD) coupled to a pillar microcavity [Nat. Nanotechnol. 12, 663 (2017)], we put forward an alternative setup for the generation of orthogonally polarized dual frequency combs and their corresponding control by using coherent two-tone cavity driving, i.e., a control laser and a probe laser. The present QD-pillar microcavity system operates in the weak-coupling regime, and this makes the experimental realization of the scheme easy. The underlying nonlinear process of the system, thanks to the QD-pillar interaction, for example, degenerate and nondegenerate four-wave mixing, results in efficient frequency comb formation. The dual combs consist of equidistant spectral lines whose spectral spacing coincides with the frequency difference between the control and probe lasers. So, programming this frequency difference between them enables us to tune both the comb-line spacing (i.e., repetition rate) and comb-line number in both vertical ( V) and horizontal ( H) polarizations. As compared with the previous approaches for dual microcomb generation, the present scheme has attractive features such as a tunable, slow repetition rate (as slow as a few megahertz), low input power (as low as a few nanowatts), and integrated compact nature in experimentally realistic operating regimes. The achievable low repetition rates are desirable to resolve narrower spectral lines and to enable use of low-power signal processing electronics.
摘要：
Feed-forward gene transcriptional regulatory networks, as a set of common signal motifs, are widely distributed in the biological systems. In this paper, the noise characteristics and propagation mechanism of various feed-forward gene transcriptional regulatory loops are investigated, including (i) coherent feed-forward loops with AND-gate, (ii) coherent feed-forward loops with OR-gate logic, and (iii) incoherent feed-forward loops with AND-gate logic. By introducing logarithmic gain coefficient and using linear noise approximation, the theoretical formulas of noise decomposition are derived and the theoretical results are verified by Gillespie simulation. From the theoretical and numerical results of noise decomposition algorithm, three general characteristics about noise transmission in these different kinds of feed-forward loops are observed. i) The two-step noise propagation of upstream factor is negative in the incoherent feed-forward loops with AND-gate logic, that is, upstream factor can indirectly suppress the noise of downstream factors. ii) The one-step propagation noise of upstream factor is non-monotonic in the coherent feed-forward loops with OR-gate logic. iii) When the branch of the feed-forward loop is negatively controlled, the total noise of the downstream factor monotonically increases for each of all feed-forward loops. These findings are robust to variations of model parameters. These observations reveal the universal rules of noise propagation in the feed-forward loops, and may contribute to our understanding of design principle of gene circuits.
